Condensed Consolidated Statements of Operations (USD $)
 3 Months Ended 9 Months Ended
Apr. 30, 2011
Apr. 30, 2010
Apr. 30, 2011
Apr. 30, 2010
Condensed Consolidated Statements of Operations        
Net sales $ 131,081,000 $ 216,303,000 $ 472,052,000 $ 521,251,000
Cost of sales 74,110,000 141,512,000 289,937,000 333,185,000
Gross profit 56,971,000 74,791,000 182,115,000 188,066,000
Expenses:        
Selling, general and administrative 22,552,000 25,628,000 69,742,000 70,256,000
Research and development 10,328,000 11,383,000 31,546,000 34,138,000
Amortization of intangibles 2,173,000 1,754,000 6,064,000 5,283,000
Merger termination fee, net 0 0 (12,500,000) 0
Total operating expenses 35,053,000 38,765,000 94,852,000 109,677,000
Operating income 21,918,000 36,026,000 87,263,000 78,389,000
Other expenses (income):        
Interest expense 2,135,000 1,980,000 6,288,000 5,913,000
Interest income and other (557,000) (315,000) (1,877,000) (728,000)
Income before provision for income taxes 20,340,000 34,361,000 82,852,000 73,204,000
Provision for income taxes 6,085,000 12,565,000 26,845,000 26,043,000
Net income $ 14,255,000 $ 21,796,000 $ 56,007,000 $ 47,161,000
Net income per share:        
Basic $ 0.54 $ 0.77 $ 2.05 $ 1.67
Diluted $ 0.47 $ 0.67 $ 1.79 $ 1.48
Weighted average number of common shares outstanding - basic 26,577,000 28,291,000 27,310,000 28,254,000
Weighted average number of common and common equivalent shares outstanding - diluted 32,378,000 34,086,000 33,069,000 34,074,000
Dividends declared per issued and outstanding common share as of the applicable dividend record date $ 0.25 $ 0 $ 0.75 $ 0